In this research, monthly data on the Frequency of Dust Storm Days (FDSD) of 44 synoptic stations of Iran during a 50-year period from 1968–2017 were used. Temporal variations in Iran's dust storms were investigated using hierarchical cluster analysis, linear regression methods, and nonparametric test of Mann Kendall. According to the cluster analysis, five climatic zones were identified with similar trends in the frequency of occurrence of dust storms including: (1) Southeast, (2) South and Central regions, (3) Western regions, (4) Eastern and Central regions, and (5) the Northern part of the country. The results of the distribution of Iranian dust storms indicated that the highest frequency of the occurrence of this phenomenon was in July, June, and May. In the seasonal period, the peak of the dust storms was concentrated in the spring and summer. Moreover, in terms of spatial analysis, in monthly, seasonal, and annual periods, the maximum FDSD in the southeastern and southern regions was much more severe than in other regions of Iran. Moreover, the slope of the changes in Iran's dust storms indicated that the trend of changes in total monthly, seasonal, and annual periods was incremental, and according to the results of the Mann–Kendall test, it was significant.

中文翻译：

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伊朗沙尘暴发生天数的时间长期变化

在这项研究中，使用了 1968 年至 2017 年 50 年间伊朗 44 个天气站沙尘暴天数 (FDSD) 的月度数据。使用层次聚类分析、线性回归方法和 Mann Kendall 的非参数检验研究了伊朗沙尘暴的时间变化。根据聚类分析，确定沙尘暴发生频率趋势相似的五个气候带包括：（1）东南部，（2）南部和中部地区，（3）西部地区，（4）东部和中部地区，以及（5）该国北部。伊朗沙尘暴分布结果表明，该现象发生频率最高的是7、6、5月份。沙尘暴的高峰期集中在春季和夏季。此外，从空间分析来看，在月、季和年期间，东南部和南部地区的最大FDSD比伊朗其他地区严重得多。而且，伊朗沙尘暴变化的斜率表明，月、季、年总周期的变化趋势是递增的，根据曼-肯德尔检验结果，具有显着性。